1. Field of the Invention
The present invention relates to a method for testing a reflection-type LCD projector. More specifically, it relates to a method for testing the digital-circuit portion of the data driver of the silicon wafer LCD of a reflection-type LCD projector, and a method for testing the panel pixel area of the silicon wafer LCD display of a reflection-type LCD projector.
2. Description of Related Art
At present, the silicon wafer liquid crystal display, which is manufactured by CMOS fabrication process, is applied to the reflection-type LCD projector. The silicon wafer liquid crystal display is characterized by integrating data drivers, scan drivers, and the pixel area onto a single insulating substrate by making the best of the high electronic mobility of the CMOS process. The structure of the silicon wafer liquid crystal display (LCD) is illustrated in FIG. 1.
For a reflection-type LCD projector using a silicon wafer liquid crystal display (or silicon wafer LCD hereafter) to project images onto a screen, its fabrication must integrate technologies including applied circuit design, driver IC (integrated circuits) design, photo-etching of patterned electrodes, filling of liquid crystals, packaging, and mounting of a back-light assembly, etc. Therefore, the silicon wafer LCD is a complicated product that relies on a highly coordinated manufacturing process. If the fabricated driver ICs can not be adequately and reliably tested, then the following steps for filling the LCD module with liquid crystals, packaging, and mounting back-light assembly can not be carried out. When the silicon wafer LCD fails to function properly during the final stages of manufacturing, then the subsequent process of debugging and reworking will prove to be costly and the real problems can not be identified and resolved. For a profit-seeking manufacturer, the subsequent waste of labor and material during mass-production stage, to fill liquid crystals, packaging, and mount back-light assembly will in time become costly.
The conventional method for testing the pixel area of the TFT-LCD panel includes a method that involves CCD image contrasting. When applying the CCD contrasting method, the panel is first back-lighted by a lighting source. The CCD device then takes an image of the pixels on the display panel, converts the image into digital data, and finally compare the data in contrast to the controlled sets of data in order to find pixel defects appearing on the display panel. However, the above described method only apply to conventional LCD manufacturing process where data drivers, scan drivers, and display panel are each fabricated and tested separately.
However, a CMOS silicon wafer LCD is an integrated device of data drivers, scan drivers, and display panel. Therefore, in order to apply the CCD image contrasting method on testing the CMOS silicon wafer LCD, the above mentioned manufacturing process of filling of liquid crystals and mounting of driver ICs and back-light assembly has to be completed before a test can be carried out. The need for a silicon wafer LCD module to be fully assembled before a functional test can be administered makes the CCD image contrast test impractical and uneconomical.
As shown in FIG. 1, the three main components to be tested on a silicon wafer LCD are the scan drivers, the data drivers, and the pixel area. Among them, the test implemented on the scan drivers only compares the input and output signals in series. The crucial task, then, is to find highly reliable and efficient testing methods for each of the data drivers and the pixel area components.
Accordingly, it is the object of the present invention to provide a highly reliable and efficient testing method for a CMOS silicon wafer LCD in a reflection-type LCD projector for the purpose of mass-production, and research and development.
A first testing method for testing the digital-circuit portion of data drivers of a silicon wafer LCD comprises the following steps:
Provide the first and the second test patterns. The first test pattern has 2n bits of digital data P1xcx9cP2n where P2jxe2x88x921=0, P2j=1, and 1xe2x89xa6jxe2x89xa6n. The second test pattern has 2n bits of digital data Q1xcx9cQ2n where Q2jxe2x88x921=0, Q2j=1.
The digital data of the first test pattern are inputted to the digital-circuit portion, and the 2n digital data are processed and outputted by the digital-circuit portion, thereby obtaining 2n bits of a first processed data Pr1xcx9cPr2n. Every value of P1, P3, xcx9cP2nxe2x88x921 processed by the digital-circuit portion is assigned to each of the respective Pr2jxe2x88x921, while every value of P2, 24, xcx9cP2n processed by the digital-circuit portion is assigned to each of the respective Pr2j.
The digital data of the second test pattern are inputted to the digital-circuit portion, and the 2n digital data are processed and outputted by the digital-circuit portion, thereby obtaining 2n bits of a second processed data Qr1xcx9cl Qr2n. Every value of Q1, Q3, xcx9cQ2nxe2x88x921 processed by the digital-circuit portion is assigned to each of the respective Qr2jxe2x88x921, while every value of Q2, Q4, xcx9cQ2n processed by the digital-circuit portion is assigned to each of the respective Qr2j.
Consequently, both a first and second testing apparatus are provided; the first testing apparatus accepts a first specific value and the first processed data Pr1xcx9cPr2n while the second testing apparatus accepts a second specific value and the second processed data Qr1xcx9cQr2n. If the first and second testing apparatuses output the first and second specific values respectively, then the digital-circuit portion processes the first and second test patterns without any error.
A second testing method for testing the display panel pixel area of a silicon wafer LCD that has M scan-lines with N pixel units located on each of the scan-lines to detect damaged pixels comprises the following steps:
(1) Divide the N pixels (data lines) into K pixel groups. Provide a group-data parallel-in series-out device. Provide a first test pattern of data length K, which is formed by outputting a first-type data and a second-type data alternately. Provide a second test pattern of data length K which is complementary to the first test pattern.
(2) Selecting one of the M scan-lines, write the first test pattern of data length K into K corresponding pixel group; wherein each pixel within the same pixel group is written with the same data value, and the N pixel units located on the selected scan-line are written with the K data of the first test pattern.
Input, in parallel, the data written into the N pixel units to the group-data parallel-in series-out device; wherein the group-data parallel-in series-out device processes the data written into every pixel within each of the K pixel groups and outputs a first processed outcome with a data length K. Complete the data output of the first processed outcome, in series, after K time cycles.
(3) Write the K data of the second test pattern into the K pixel groups respectively; where each pixel within the same pixel group has the same data, and the N pixels are written with the K data of the second test pattern.
Input, in parallel, the data written into the N pixel units to the group-data parallel-in series-out device; wherein the group-data parallel-in series-out device processes the data written into every pixel unit within each of the K pixel groups and outputs a second processed outcome with a data length K. Complete the data output of the second processed outcome, in series, after K time cycles.
(4) Repeat the above steps (2) and (3) until all of the M scan-lines are tested completely; wherein, when each of the M scan-lines is tested according the above steps, the first test pattern is contrasted with the first processed outcome while the second test pattern is contrasted with the second processed outcome in order to detect any damaged pixels.